Process for producing a convex sail or a tensile structure

ABSTRACT

A process for modelling a sail with a sandwich configuration and a three-dimensional convex shape, wherein the “mould” is formed by a semirigid film material which has a shape identical to that of the sail to be produced. On this kind of “parent sail”, a cloth is prepared by adhering, by means of a removable adhesive, synthetic weft ( 1 ) and warp ( 2 ) filaments onto the “parent sail”. This cloth will form the inner layer of the final “sandwich”. Two thin external plastic laminates are applied on the cloth, one on each side, after removal of the cloth from the “parent sail”. The thin external plastic laminates are applied in individual pieces adapted to follow the convexity of the cloth. The application of the external laminates is performed on a plane support.

TECHNICAL FIELD

The present invention relates to a triangular or trapezoidal sheet whichcan be utilized as a sail for sailboats. As already known, modern sheetsused as sails for sailboats, are preferably produced in the form of asandwich structure, in which two external plastic laminates are joinedby an appropriate adhesive material or in another way, enclosingtherebetween reinforcement filaments made of Kevlar, Spectra, Polyesteror some other kind of resistant synthetic material.

BACKGROUND ART

According to the the prior art, plastic filaments are laid in threadgroups, using an automated mechanism, onto a plastic film previously puton a convex and rigid mould, and subsequently they are covered by asecond film having the same features as the first one. A considerabledrawback of known production processes lies in the complexity of theautomated plant, comprising the rigid adjustable mould and the robotwhich puts the reinforcement filaments on the first plastic laminatelaid onto the rigid convex mould. In order to allow the adjustment ofthe mould, the latter must be provided with a plurality of flexiblefillets or strips, which are nevertheless substantially rigid and whichare provided with associated pneumatic cylinders to be adjustedindividually depending on the value of the sail's camber.

Further problems must be faced when a different mould must beconstructed for a sail of different size.

DISCLOSURE OF THE INVENTION

An object of the present invention is to realize a sail productionprocess, which is less expensive than the traditional process, byreplacing the known rigid mould, with a mould which in the followingdescription will be called the “parent sail” (“loom”).

This definition is useful to emphasize—not only in terms of costs—thedifference with respect to the traditional rigid and adjustable mould.

Another most important object of the present invention is that ofrealizing a “cloth” on said parent sail. In fact, the “parent sail” is a“fictitious sail” made of thermoplastic material, for instance apolyester film, which is much thicker than a plastic laminate used inpractice to make sails. The parent sail is only used for the purpose ofmodelling, according to the desired camber and dimensions, a cloth madeof reinforcement filaments (Kevlar, Spectra, polyester, etc.), which isto be introduced between the plastic laminates of the sail, in order toform a “sandwich”.

Since the parent sail has a negligible cost with respect to knownadjustable rigid moulds, it may be realized according to differentshapes (cambers) and different dimensions corresponding to those ofknown sails for sailboats. Preferably, a polyester film of 250 micron ofthickness (10 mils) will be used, which forms a common extrusionmaterial of a commercial kind.

Once the cloth has been realized, which is very different from theensemble of reinforcement filaments arranged between the plasticlaminates in a traditional sail—as will be explainedafterwards—conventional (vacuum) techniques will be used for applyingthe thin external plastic laminates.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be illustrated in more detail with referenceto a preferred embodiment thereof, which is shown in FIG. 1, only forillustrative and non-limitative purposes.

FIG. 1 shows the structural cloth obtained on the “parent sail”, whichis afterwards introduced, like in a “sandwich”, between two outerplastic laminates, in order to form the sail.

BEST MODE OF CARRYING OUT THE INVENTION

In the present process, the “parent sail” is realized in the same way asa sail made of a very thin plastic laminate, according to thetraditional process.

The camber of the parent sail and its dimensions will obviously beidentical with those of the sail to be obtained.

Once the parent sail has been realized, the cloth is formed on the same,and this cloth will constitute the inner layer of the sandwich formingthe sail to be realized.

The cloth is made to adhere to the parent sail by means of a quicksetting removable adhesive, so that it remains “welded” thereon, and sothat each thread will have the desired length according to the arcwhereon it lies.

Once this operation is terminated, and after having obtained the desiredtriangular cloth, which is shown in FIG. 1, the cloth will be removedfrom the parent sail and the vacuum lamination will start according toknown techniques.

The cloth (FIG. 1) is much thicker (more closely woven) than the net ofreinforcement filaments of the known processes. The cloth includes awarp 2 and a weft 1. FIG. 1 shows a homogeneous-type cloth having thesame size as the sail and including a weft 1 and a warp 2, wherein twoclose parallel filaments of the warp and the weft, are preferablyarranged at a distance less than 1 cm.

Each lateral plastic laminate of the sandwich, which is not shown inFIG. 1, is not made of a single piece. Actually, each laminate isapplied on the perfectly pliable cloth (FIG. 1), in pieces of about 1meter of height and variable length.

The cloth will be arranged onto a plane support, and since the cloth hasa convex shape, the respective piece of plastic laminate will have alength varying according to where the piece of plastic laminate must beapplied, on condition that it can follow the local convexity of thecloth. It is obvious that pieces having the greatest possible length andensuring at the same time perfect adherence of the individual piece ofplastic laminate to the cloth will be used in the production process.

Industrial Applicability

The advantage of the present invetion is that once the cloth has beenprepared, the latter forms a valid three-dimensional support, which isperfeclty pliable and made of close filaments, whereon it is possible toapply, one at a time, on a plane, the two external plastic laminates.

The process of the present invention is not limited to the specificconfiguration of the cloth which is shown in FIG. 1.

It is obvious that the plastic laminates are those normally used in thisfield, e.g. with the required elasticity, reduced weight, highmechanical resistance, resistance to heat, UV rays and optimumimperviousness. In this case and in the case of the cloth, manydifferent materials known to those skilled in the art may be employed,so that it is worthless to mention them explicitly.

It is also evident that in the above description nothing has been saidabout other already known operations, like e.g. the application ofsuitable reinforcements at the sail's corners A,B,C, or the like.

What is claimed is:
 1. A process for producing a sail or a cover elementof a tensile structure having a triangular or trapezoidal form,characterized in that on a parent sail consisting of a semirigid filmmaterial of the same shape and size as that of the desired product, athick cloth of synthetic filaments is formed, including horizontal weftfilaments (1) and vertical warp filaments (2), the said cloth being madeto adhere to the parent sail by means of a removable adhesive and beingused for applying thereon two external plastic laminates, after the saidcloth has been removed from the parent sail, wherein the externalplastic laminates are applied in individual pieces on both sides of thecloth, in such a way as to adapt themselves and follow the localconvexity of the cloth, and this operation is carried out on a planesupport.
 2. A process for producing a sail or an element of a tensilestructure according to claim 1, characterized in that the distancebetween the synthetic weft filaments (1) is less than 1 cm, and thatbetween the synthetic warp filaments (2) is also less than 1 cm.
 3. Aprocess according to claim 2 characterized in that the thickness of theparent sail is about 250 micron (10 mils).
 4. A process according toclaim 1, characterized in that the height of the pieces which form eachexternal plastic laminate is equal to about 1 m.
 5. A sail or element ofa tensile structure, having a polygonal form, produced according to theprocess of claim 1, comprising two external plastic laminates, which areformed by a plurality of pieces, wherein said pieces are joined to eachother at their edges, and comprising also an inner convex-shaped cloth,which is flexible and has the same form and size of the sail to berealized; the said cloth including horizontal synthetic weft filaments(1) and vertical synthetic warp filaments (2), arranged in such a way asto form a homogeneous cloth.
 6. A sail or an element of a tensilestructure, according to claim 5, characterized in that the mutualdistance between the weft filaments (1) is less than 1 cm, and thedistance between the warp filaments (2) is also less than 1 cm.
 7. Asail according to claim 6, characterized in that the pieces which formthe external plastic laminates of the sail's “sandwich”, have a sizeallowing them to follow the curvature of the flexible internal clothwithout folds and crease.